Use provided port to get current instance id

In Job #60042, it tried to run openstack server remove port but failed.

From the error message, it looks like it's missing a argument. We clearly defined variable OOD_PORT so it's the CURRENT_INSTANCE_ID. We used floating ip to get the CURRENT_INSTANCE_ID which is based on assumption that the port and floating ips are associated with the same instance at the same time.

Since we want to detach the port when it's in use. The floating ip is really not related here. We should get the instance id directly by checking the provided port id.